Crystal structure of the 'mixed-layer' Aurivillius phase Bi5TiNbWO15

The crystal structure of the Aurivillius phase Bi5TiNbWO15 has been analyzed in detail using powder X-ray and neutron diffraction. The structure can be described as a regular intergrowth of alternating single and double perovskite-like layers sandwiched between fluorite-like bismuth oxide layers, such that the layer sequence is ... [WO4]-[Bi2O2]-[BiTiNbO7]-[Bi2O2] .... There is complete ordering of tungsten within the B sites of the single perovskite layer, so that the structure can be described as a direct intergrowth of the 'component' Aurivillius phases B2WO6 and Bi3TiNbO9. At 25degreesC the structure adopts the polar orthorhombic space group 12cm, a = 5.4231(2) Angstrom, b = 5.4027(2) Angstrom, c = 41.744(1)Angstrom. (C) 2004 Elsevier Inc. All rights reserved.